If I was responsible for choosing a cryptocurrency for Amazon, I would use Nano. It offers instant and zero fee transactions with far greater scalability than Litecoin.
Bitcoin faces increasing competition from coins with superior technology such as Ethereum. Incoming capital from fiat is invested mainly in altcoins and ICOs therefore Bitcoin may never reach $20,000.
I have been with them for about 4 months and never had any problem. They have fixed and narrow spreads and I have not noticed any price inconsistences compared to esignal data. All my orders have been executed without any problems.